我们已经知道三角形三个内角度数的和是180°，（1）你能运用这个知识求出四边形、五边形、六边形等多边形的内角和吗？（2）你发现的规律是什么？ （3）请用字母式子表示n边形内角和．
直接写得数+=﹣=×=×5= 2﹣= 3÷7=÷=÷4=
直接写出得数．+﹣×6×24× 5÷4.8 （+）×6 9×0+（+）÷ 12×11×× 1.5﹣+﹣．
直接写出得数． 1÷= 1﹣﹣=×==×12=（3+）×0=÷=+=
计算：﹣= 18×===×12=÷2=+=﹣=
===================== 2.5×16======== 1.5÷0.05== 1.5÷0.05==== 2.5×0.4============ 6.25+1.75===============
+
=
﹣
=
×
=
×5=
= 3÷7=
÷
=
÷4=
+
﹣
×6
×24
×
5
÷4.8
+
）×6 9
×0+
（
+
12×11×
×
1.5﹣
﹣
．
= 1﹣
﹣
×
=
=
×12=（3
+
）×0=
÷
=
+
=
﹣
= 18×
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×12=
÷2=
+
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﹣
=
=
=
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=
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=
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= 2.5×16=
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=
=
=
=
= 1.5÷0.05=
= 1.5÷0.05=
=
=
= 2.5×0.4=
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=
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= 6.25+1.75=
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